Segments and Related Information (Schedule of Financial Information by Reportable Segment - Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Capital Expenditures:
Capital expenditures	$ 84,410	$ 109,254	$ 126,288
Continuing Operations [Member]
Capital Expenditures:
Capital expenditures	84,400	109,300	126,100
Reportable Segments [Member] | Communications [Member]
Capital Expenditures:
Capital expenditures	25,800	23,400	25,100
Reportable Segments [Member] | Oil and Gas [Member]
Capital Expenditures:
Capital expenditures	38,100	44,200	67,400
Reportable Segments [Member] | Electrical Transmission [Member]
Capital Expenditures:
Capital expenditures	13,000	25,800	17,600
Reportable Segments [Member] | Power Generation and Industrial [Member]
Capital Expenditures:
Capital expenditures	3,500	6,700	5,700
Reportable Segments [Member] | Other [Member]
Capital Expenditures:
Capital expenditures	200	0	0
Corporate [Member]
Capital Expenditures:
Capital expenditures	$ 3,800	$ 9,200	$ 10,300